Скачать или смотреть How to Store User-Entered Values in an Array in C+ +

Learn how to correctly store user input values in a vector in C+ + . This guide breaks down the solution to common mistakes when using vectors in C+ + .
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This video is based on the question https://stackoverflow.com/q/64030141/ asked by the user 'Martin Schmitz' ( https://stackoverflow.com/u/12820052/ ) and on the answer https://stackoverflow.com/a/64030301/ provided by the user 'Chass Long' ( https://stackoverflow.com/u/9363736/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Storing User-Entered Values in an Array in C+ +

Are you trying to read multiple integers from user input and store them in a C+ + array (or vector) but encountering issues with your code? You're not alone! This is a common problem, especially for those who are starting out with C+ + . In this post, we will break down a simple solution to properly store a set of integers entered by the user.

Understanding the Problem

Let's say you want to write a program that allows a user to enter a positive integer n, indicating how many numbers they would like to input. Following that, your program should read these n integers and store them in a vector.

For instance, if the user inputs "3 1 2 3", the expected output should be:

[[See Video to Reveal this Text or Code Snippet]]

However, if your code doesn't work as intended and instead outputs zeroes or unexpected values, it could be due to how you're managing the vector, so let's take a closer look.

The Original Code Problem

Here is a simplified version of code that a user might write to achieve this functionality:

[[See Video to Reveal this Text or Code Snippet]]

What Went Wrong?

The issue arises from the misuse of push_back() on the vector. By initializing the vector with a fixed size of n, you are already reserving space for n integers. However, when you use push_back(), it adds new elements to the end of the vector, resulting in unwanted default values (zeros in this case) being printed out.

Solution: Correctly Storing Values in the Vector

To solve this problem, you need to replace the push_back() method with direct assignment to the vector's indexed positions. Here’s the corrected code:

[[See Video to Reveal this Text or Code Snippet]]

Key Changes Made

Initialization: The vector is still initialized with size n, which is correct.

Input Assignment: Instead of using push_back(), we directly assign the input value m to vec[i], where i is the index of the vector.

Output: The output remains unchanged, but now it will reflect the user input correctly.

Conclusion

By following this guide, you should now understand how to correctly store user-entered values in a vector in C+ + . It's simple adjustments like these that can solve issues and improve your code significantly. If your goal is to read multiple integers and store them, remember to use indexing instead of methods like push_back() when you have already defined the size of your vector.

Happy coding!